An image forming apparatus which employs an electrophotographic printing method is arranged as below. Toner, which is a component of a developer, is supplied from a developing device to an electrostatic latent image which is formed on a surface of a photoreceptor, so that a toner image which is an visible image is formed. The toner image is transferred to recording paper or the like which serves as a transfer medium. Then, a solid recording image is formed by fixing the toner image transferred to the recording paper.
The recent spread of color ink-jet image forming apparatuses requires smaller and lower-priced image forming apparatuses each employing an electrophotographic printing method.
In view of the circumstances, a nonmagnetic monocomponent developing method, which has a simple structure and can be smaller, is frequently used for a developing device to be provided in an image forming apparatus which employs an electrophotographic printing method.
For example, Patent Literature 1 describes a color electrophotographic video apparatus which forms a full color image by single-step development. A developing unit of the color electrophotographic video apparatus described in Patent Literature 1 is arranged such that a transportation device which carries toner contained in the developing unit and is a meshed belt is sandwiched between two plates of a friction device. This brings the toner which has been carried by the transportation device into contact with the two plates of the friction device. Friction between the toner and each of the two plates charges the toner.